FIG. 1 (PRIOR ART) is a representation of an analog signal containing video information according to the RS170A video signal standard. FIG. 2 (PRIOR ART) is a simplified view of the screen of a cathode ray tube 20 (CRT) upon which video information contained in the signal of FIG. 1 is displayed. A first vertical blanking pulse 10 of the analog signal shown in FIG. 1 causes an electron beam in the CRT to be blanked out while synchronization pulse 10a causes the beam to be positioned at the upper left corner of the CRT. After the vertical blanking pulse 10, the electron beam is swept from left to right across the screen in a slightly downward path as indicated by line L1 in FIG. 2. Video information 11 for line L1 is contained between the end of the first vertical blanking pulse 10 and the beginning of a first horizontal blanking pulse 12. After the electron beam reaches the right edge of the screen, the first horizontal blanking 12 pulse causes the beam to be blanked while horizontal synchronization pulse 12a causes the beam to move from right to left back to the far left of the screen. At the end of the first horizontal blanking pulse 12, the beam again sweeps from left to right in a slightly downward path along line L2 across the screen. Video information 13 for the second line L2 is located between the first horizontal blanking pulse 12 and a second horizontal blanking pulse 14. Once the beam arrives at the right edge of the screen, a second horizontal synchronization pulse 14a causes the beam to be moved to the left edge of the screen. This sequence of writing successive lines of video information onto the screen is repeated until midway through line L262. A second vertical blanking pulse 15 then causes the beam to be blanked and moved to point P262.5 at the center of the top edge of the screen. The remainder of line L262 of video information is then swept across to the right edge of the screen. Successive horizontal synchronization pulses (not shown) which occur after second vertical blanking pulse 15 repeatedly blank and return the beam to the left edge of the screen until lines L263-L525 have been interlaced with lines L1-L262 on the screen. According to the RS170A standard, 525 lines of video information constitute one "frame" of video information. Transmission standards other than the RS170A standard may have frames with more or fewer lines of video information.
Some prior art devices store a frame of digitized video information in a memory called a frame store memory. These prior art devices typically digitize incoming video information and then store the video information, line by line, into the frame store memory until all the desired video information from the frame is stored in the frame store memory. Once stored, the frame of video information may be read out of the frame store. Although such prior art video capture devices may function in their intended applications, such prior art devices tend to be costly due to the provision of a frame store memory with the capacity to store all the video information pertaining to one or more frames.